Fire behavior of a floor covering based on linoleum and cork

ABSTRACT

The present invention relates to a floor covering based on linoleum having improved fire-protection properties, comprising at least one wear layer made of linoleum, which contains at least one phosphorus-containing compound, solution, suspension, or dispersion as a liquid/viscous flame retardant in a quantity of up to 20 weight-percent, in relation to the quantity of the wear layer, as well as a method for the manufacture thereof. Furthermore, the present invention relates to a floor covering based on cork having improved flame protection properties, comprising at least one phosphorus-containing compound, solution, suspension, or dispersion as a liquid/viscous flame retardant in a quantity of up to 20 weight-percent, in relation to the quantity of the wear layer.

The present invention relates to a floor covering based on linoleumhaving improved flame-protection properties, including at least one wearlayer made of linoleum, which contains at least onephosphorus-containing compound, solution, suspension, or dispersion as aliquid/viscous flame retardant in a quantity of up to 20 weight-percent,in relation to the quantity of the wear layer, as well as a method forthe manufacture thereof. Furthermore, the present invention relates to afloor covering based on cork having improved flame protectionproperties, including at least one phosphorus-containing compound,solution, suspension, or dispersion as a liquid/viscous flame retardantin a quantity of up to 20 weight-percent, in relation to the quantity ofthe wear layer.

Floor coverings based on linoleum and methods for their manufacture havebeen known for some time. However, a disadvantage of the linoleum-basedfloor coverings known in the related art is the critical behavior infire. Linoleum only reaches building material class B1 with difficulties(fire testing according to DIN 4102 T14, “Radiant Foreign Panel Test”).In the future, the requirements for floor coverings are to be sharpenedby a new EN norm. For example, currently a linoleum floor covering mustreach a critical radiation intensity of ≧4.5 kW/m² in accordance withDIN 4102 T14 in order to be classified in the economically importantbuilding material class B1. Upon a future introduction of the novel testmethods according to EN ISO 9239-1 and EN ISO 11925-2, which is similarto the old test DIN 4102 T14, but whose classification is performedaccording to prEN 13501-1, floor coverings, particularly linoleum,having a test result of ≧4.5 kW/m² are no longer classified in B1, butrather in C_(FL). Significant competitive disadvantages in relation toother plastic floor coverings, such as PVC, may arise from this. Only ata critical radiation intensity of ≧8 kW/m² would the classification inthe economically important material class B_(FL) be possible. Thecritical fire behavior is also a disadvantage of the cork-based floorcoverings known in the related art.

Therefore, the present invention is based on the object of providing afloor covering based on linoleum or cork which is to have significantlyimproved fire behavior in comparison to the linoleum or cork floorcoverings known in the related art.

This object is achieved by the features characterized in the claims.

In particular, a floor covering based on linoleum is provided,comprising at least one wear layer made of linoleum which contains atleast one phosphorus-containing compound, solution, suspension, ordispersion as a liquid/viscous flame retardant in a quantity of up toapproximately 20 weight-percent, preferably up to approximately 10weight-percent, in relation to the quantity of the wear layer.

The liquid/viscous flame retardant is preferably selected from the groupof phosphates, phosphites, phosphonates, organically substitutedphosphonates, and mixtures thereof. Examples of organically substitutedphosphonates are cyclic or acyclic esters of organic phosphonic acids,such as diesters, e.g., dimethyl propane phosphonate. According to afurther preferred embodiment of the present invention, anaqueous/oleaginous dispersion containing red phosphorus may be used asthe liquid/viscous flame retardant. This may be stabilized andmicroencapsulated red phosphorus, wherein water or castor oil may beused as the carrier. The phosphorus content is preferably between 40 and60 weight-percent, in relation to the total dispersion. Of course, amixture made of red phosphorus and at least one of the above-mentionedliquid/viscous flame retardants may also be used.

According to the present invention, a liquid/viscous flame retardant isunderstood as a flame retardant having a dynamic viscosity of up toapproximately 40,000 Pa.s (100° C.), preferably up to 5000 Pa.s (100°C.), especially preferably up to 200 Pa.s (100° C.).

The additional flame retardants usable in the wear layer made oflinoleum are not subject to any special restriction and, for example,the flame retardants known in the related art from the group ofcarbonization-promoting and fire-smothering flame retardants, such asammonium phosphate or dipentaerythritol, the flame retardants which forma barrier layer, such as borates and aluminum polyphosphates, the solidinorganic flame retardants, and the flame retardants which form aninsulating layer and/or intumescence agents may be used. Furthermore,halogenated organic compounds, such as chlorinated paraffins, orhalogenated organic phosphorus compounds may be used as an additionalflame retardant. Solid inorganic flame retardants are understood toinclude, for example, inorganic compounds, such as aluminum oxidehydrates, borates, e.g., zinc borates, ammonium phosphate, antimonyoxides, aluminum hydroxides, preferably aluminum trihydroxide, andmagnesium hydroxide, aluminum hydroxide and magnesium hydroxide alsobeing referred to as water-releasing flame retardants. The proportion ofthe solid inorganic flame retardant is preferably up to approximately 60weight-percent, especially preferably up to approximately 30weight-percent, in relation to the quantity of the wear layer. The solidinorganic flame retardant aluminum trihydroxide is especially preferred.These flame retardants may be provided in the linoleum wear layer singlyor as a mixture containing at least two of these flame retardants (fromthe same or different of the above-mentioned groups).

Furthermore, the processing properties may be significantly improved byadditionally incorporating water glass (i.e., an “internal frame” formsin the mixed compound and thus stiffens the mixed compound) and thematuring time may be significantly shortened. The usable water glass,which is a flame retardant forming a barrier layer, is sodium silicate,for example. A mixture of at least two different flame retardants whichform a barrier layer, i.e., water glass in combination with one or moreof the above-mentioned flame retardants which form a barrier layer, forexample, may also be used in the linoleum wear layer. Water glass may beprovided in the wear layer made of linoleum in a quantity of up toapproximately 15 weight-percent, in relation to the quantity of the wearlayer.

In contrast to the typical understanding that highly alkaline substanceshave a destructive effect on the structure of the linoleum, ifadditional water glass is used in proportions up to 15%, it may bedetermined, surprisingly, that the pH value is regulated via the acidsnaturally contained in the linoleum cement and the acids arising duringthe cement cooking and the maturing.

Furthermore, if sodium silicate is used, for example, it may bedetermined that this water glass may be polycondensed in a long chain inprinciple and an “internal frame” is thus formed in the linoleumcompound, which, in connection with the oxidative maturing of thelinoleum, leads to a more rapidly hardening material having improvedproperties with regard to fire behavior, degree of hardness,flexibility, abrasion, etc., for example. In addition, if water glass isused in connection with the liquid/viscous flame retardants according tothe present invention, the stiffening properties of water glass may beapproximately canceled out by a saponification process of theliquid/viscous flame retardant, the salts which are released acting as apH buffer and the linoleum compound able to be kept essentially pHneutral.

Furthermore, the wear layer made of linoleum comprises typicalcomponents, such as binders (Bedford cement or B cement made ofpartially-oxidized linseed oil and at least one resin as a tackifier),at least one filler, and if necessary at least one coloring agent.Typically, softwood flour and/or cork flour (if wood flour and corkflour are present simultaneously, typically in the weight ratio 90:10)and/or chalk, kaolin (China clay), diatomaceous earth, and heavy sparare used as fillers. In addition, precipitated silicic acid and smallquantities of water glass, for example, water glass in a quantity of upto 15 weight-percent in relation to the quantity of the wear layer, maybe added to stiffen the mass.

The linoleum mixed mass typically contains at least one coloring agent,such as a pigment (e.g., titanium dioxide), and/or other typicalcoloring agents based on inorganic and organic dyes. Any natural orsynthetic dyes as well as inorganic or organic pigments, alone or in anyarbitrary combination, may be used as coloring agents.

A typical linoleum composition contains, in relation to the weight ofthe wear layer, approximately 40 weight-percent binder, approximately 30weight-percent organic materials, approximately 20 weight-percentinorganic (mineral) fillers, and approximately 10 weight-percentcoloring agents. Furthermore, typical additives, such as processingaids, antioxidants, UV stabilizers, lubricants, and the like, which areselected as a function of the binder, may be contained in the linoleummixed mass.

In addition, the floor covering based on linoleum according to thepresent invention may be implemented as electrically conductive byadding at least one derivative of imidazole, imidazoline, benzimidazole,or morpholine, or a cationically-active compound (cf. DE 34 16 573 andWO 99/10592) and/or by positioning a layer based on linoleum, whichcontains at least one electrically conductive filler, such as carbonblack or metal powder, under the linoleum wear layer. Of course, anelectrically conductive layer of this type may also contain one or moreof the above-mentioned flame retardants.

The linoleum wear and/or top layer preferably has a thickness of 0.9 to6.0 mm, especially preferably 1.4 to 4 mm. In the scope of the presentinvention, the wear layer is understood as the uppermost layer of thefloor covering, made of a homogeneous material.

The floor covering based on linoleum according to the present inventionmay be carrierless (cf. DE 199 10 389 A1) or include a carrier. Amaterial based on natural or synthetic woven or knitted fabrics ortextile materials may be used as the carrier material. Examples are jutefabrics, mixed fabrics made of natural fibers, such as cotton and rayonfiber, glass cloth, glass cloth coated with adhesive-promoting agent,mixed fabrics made as synthetic fibers, fabrics made of core/mantelfibers having a core made of polyester and a mantel made of polyamide,for example. For example, a coating of the glass fibers made of astyrene-butadiene latex may be used as the adhesive-promoting agent forglass cloth.

The floor covering according to the present invention may be implementedwith or without a carrier, the linoleum wear layer able to be designedas both single-layer and multilayered. In this case, depending on thelayer sequence, both symmetrical and asymmetrical sheet materialsresult, symmetrical constructions being preferred for carrierlesslinoleum sheet materials. For example, the floor covering according tothe present invention may include two layers made of linoleum(materially homogeneous), which may be identical or different.

Furthermore, a corkment layer with or without a carrier may bepositioned under the linoleum wear layer. Corkment is a mixture whichcontains B cement and milled cork as a filler and ensures better thermalinsulation, impact elasticity, and walking comfort and damps the impactand airborne noise as an insulating underlayer in floor coverings. Acorkment layer of this type may also include one or more of theabove-mentioned flame retardants.

In addition, functional layers may also be positioned under or betweentwo linoleum layers, so that three-layered or multilayered sheetmaterials result. For example, at least one further layer, preferably afoam layer, a layer for impact noise damping, and/or an insulation layermay be positioned under the wear layer of the floor covering accordingto the present invention. The layer thicknesses of the applied layersmay be identical or different. All of these functional layers positionedunder or between two linoleum layers may also each contain one or moreof the above-mentioned flame retardants.

Furthermore, at least one adhesive layer may be positioned on the backof the floor covering according to the present invention without acarrier.

The floor covering based on linoleum according to the present inventionmay be provided in the form of webs or tiles.

For example, the floor covering based on linoleum according to thepresent invention may be manufactured through typical methods formanufacturing single-layer or multilayered linoleum floor coverings withor without a carrier. Preferably, during the processing of linoleumcements, which are manufactured from drying vegetable oils and/or fatsand tree resins in accordance with the requirements of DIN EN 548,phosphates, phosphites, phosphonates, organically substitutedphosphonates or mixtures thereof are already added at the step of theoil oxidation process in order to cause a reaction of theabove-mentioned phosphor compounds with free double bonds, for example,or esterification with existing OH groups or at least achieve intimatebinding (mixing) with the linoleum cement.

Furthermore, the present invention provides a typical method formanufacturing a floor covering based on linoleum, comprising at leastone wear layer made of linoleum, which contains at least onephosphorus-containing compound, solution, suspension, or dispersion as aliquid/viscous flame retardant in a quantity of up to 20 weight-percent,in relation to the quantity of the wear layer, in which the linoleummixed mass containing at least one liquid/viscous flame retardant isprocessed, using calenders or rolling mills, into a floor covering withor without a jute carrier. According to a preferred embodiment of themanufacturing method according to the present invention, as definedabove, at least one material from the group of phosphates, phosphites,phosphonates, organically substituted phosphonates, and mixtures thereofmay be selected as the liquid/viscous flame retardant. According to afurther preferred embodiment, as defined above, an aqueous/oleaginousdispersion containing red phosphorus or a mixture made of red phosphorusand at least one of the above-mentioned liquid/viscous flame retardantsmay also be used.

Furthermore, the present invention provides a floor covering based oncork, comprising at least one phosphorus-containing compound, solution,suspension, or dispersion as a liquid/viscous flame retardant in aquantity of up to approximately 20 weight-percent, preferably up toapproximately 10 weight-percent, in relation to the quantity of the wearlayer.

The liquid/viscous flame retardant is preferably selected from the groupof phosphates, phosphites, phosphonates, organically substitutedphosphonates, and mixtures thereof. Examples of organically substitutedphosphonates are cyclic or acyclic esters of organic phosphonic acids,such as diesters, e.g., dimethyl propane phosphonate. According to afurther preferred embodiment of the present invention, anaqueous/oleaginous dispersion containing red phosphorus may be used asthe liquid/viscous flame retardant. This may be stabilized andmicroencapsulated red phosphorus, wherein water or castor oil may beused as the carrier. The phosphorus content is preferably between 40 and60 weight-percent, in relation to the total dispersion. Of course, amixture made of red phosphorus and at least one of the above-mentionedliquid/viscous flame retardants may also be used.

The liquid/viscous flame retardant is preferably the liquid/viscousflame retardant defined above. The flame retardants additionally usablein the floor covering based on cork are not subject to any specialrestriction and, for example, the flame retardants known in the relatedart from the group of carbonization-promoting and fire-smothering flameretardants, such as ammonium phosphate or dipentaerythritol, the flameretardants which form a barrier layer, such as borates and ammoniumpolyphosphates, the solid inorganic flame retardants, and the flameretardants which form an insulating layer and/or intumescence agents maybe used. Furthermore, halogenated organic compounds, such as chlorinatedparaffins, or halogenated organic phosphorus compounds may be used as anadditional flame retardant. Solid inorganic flame retardants areunderstood to include, for example, inorganic compounds, such asaluminum oxide hydrates, borates, e.g., zinc borates, ammoniumphosphate, antimony oxides, aluminum hydroxides, preferably aluminumtrihydroxide, and magnesium hydroxide, aluminum hydroxide and magnesiumhydroxide also being referred to as water-releasing flame retardants.The solid inorganic flame retardant aluminum trihydroxide is preferred.These flame retardants may be provided in the cork wear layer singly oras a mixture containing at least two of these flame retardants (from thesame or different of the above-mentioned groups).

In a further preferred embodiment, the floor covering based on corkcontains water glass in addition to the at least one liquid/viscousflame retardant, water glass preferably being contained in a quantity ofup to approximately 15 weight-percent, in relation to the quantity ofthe wear layer.

To manufacture a cork floor covering of this type according to thepresent invention, typically cork granulate of a specific grain sizedistribution and residual moisture (preferably 1.5-3.0%) is mixed withmelamine-formaldehyde resin as a binder and the flame retardants usedaccording to the present invention described above and a typicalcross-linking catalyst, the binder component typically being 10-30weight-percent in this case, since a part of the binder is bound by theflame-retardant additives. This mixture is poured into thick-walledsteel forms (exemplary dimensions: width 700 mm, length 1000 mm, height800 mm) and compressed (preferably 10-200 tons). The cross-linking isperformed at 110-135° C. within 8 to 22 hours, for example. The blocksmanufactured in this way from cork granulate (having a residual heightof 100-300 mm depending on the degree of compression/pressure, forexample) are then cut/peeled into individual slabs using a band cuttingfacility. The slab thickness may be between 1 and 10 mm, for example. Inorder to achieve a smooth surface with a sharp contour, the slabs aretypically ground and calibrated using a belt grinding machine. The topis preferably ground in this case using 3 to 6 grinding passes,initially with a coarse abrasive grit and finally with a fine abrasivegrit (for example, 1st=40 grit, 2nd=80 grit, 3rd=120 grit, 4th=180 grit,5th=220 grit, 6th=360 grit). The bottom is only ground with 1-2 grindingpasses, for example with 24 and 40 grit. The slabs may subsequently beequipped with a surface protection. This may be performed, for example,using a PVC clear film (K value 60 or 80), a lacquer (PPG or Lott), orwax (for example, wax types: solid floor wax, Loba, Ditzingen Germany).Subsequently, tile-shaped slabs may be stamped out of the coated slabsand the edges may be cleaned up using cutters if necessary. The corkslabs manufactured in this way achieve a critical radiation strength ofgreater than 8 kW/m² and a fire progress of less than 150 mm within 20seconds in accordance with EN ISO 9239-1, corresponding to aclassification of B_(FL) in accordance with prEN 13501-1:1999.

The present invention and further advantages resulting therefrom will bedescribed in greater detail in the following description with referenceto the embodiments described in the examples.

EXAMPLES

Linoleum Floor Covering

First, all of the components for the linoleum compounds listed in thefollowing Table 1 are mixed in a suitable mixing unit into a basic mass(mixed mass) which is as homogeneous as possible. The mixed massobtained is processed into rough sheets by a rolling mill and suppliedto a grater and/or granulator, after which the mixed mass particles thusobtained are supplied to a calender and pressed onto jute as a carriermaterial under pressure and a temperature typically from 10° C. to 150°C.

A formulation according to the present invention is listed as an examplein Table 1, the values specified relating to weight-percent in relationto the quantity of the total mixture (wear layer). The individualcomponents of the formulation specified in Table 1 are to be selected insuch a way that the value 100 weight-percent results for the wear layerfor each specific formulation. TABLE 1 Formula (Weight-percent) Cement30-55 Cork flour  0-25 Wood flour  5-45 Chalk  0-60 Titanium dioxide 1-15 Colored pigments 0-5 Diatomaceous earth 0-8 Zinc oxide 0-5Aluminum trihydroxide  0-60 Liquid/viscous flame retardant 0.01-20  

The formulation listed in Table 1 and/or the linoleum floor coveringmanufactured therefrom shows, because of the liquid/viscous flameretardants used according to the present invention and possibly furtherflame retardants, drastically improved flame protection properties incomparison to a typical linoleum floor covering without flameretardants, with properties which otherwise remain the same.

1. A floor covering based on linoleum, comprising at least one wearlayer made of linoleum, which contains at least onephosphorus-containing compound, solution, suspension, or dispersion as aliquid/viscous flame retardant in a quantity of up to 20 weight-percent,in relation to the quantity of the wear layer, wherein the wear layerfurther contains water glass.
 2. The floor covering according to claim1, wherein the liquid/viscous flame retardant is selected from the groupof phosphates, phosphites, phosphonates, organically substitutedphosphonates, an aqueous/oleaginous dispersion containing redphosphorus, and mixtures thereof.
 3. The floor covering according toclaim 1, wherein the wear layer made of linoleum additionally comprisesa flame retardant from the group of carbonization-promoting andfire-smothering flame retardants, flame retardants which form a barrierlayer, intumescence agent solid inorganic flame retardants, or mixturescontaining at least two of these additional flame retardants.
 4. Thefloor covering according to claim 3, wherein the solid inorganic flameretardant is aluminum trihydroxide.
 5. The floor covering according toclaim 1, wherein the wear layer contains water glass in a quantity of upto 15 weight-percent, in relation to the quantity of the wear layer. 6.A method for manufacturing a floor covering based on linoleum,comprising at least one wear layer made of linoleum, which contains atleast one phosphorus-containing compound, solution, suspension, ordispersion as a liquid/viscous flame retardant in a quantity of up to 20weight-percent, in relation to the quantity of the wear layer, in whichthe linoleum mixed mass containing at least one liquid/viscous flameretardant is processed into a floor covering using calenders or rollingmills.